Spam or worse: no message and a "cannot connect" when I rang from a different phone

calls and then hangs up straight away, its happened 3 times within the last 24 hours

Caller: Claiming to be Telstra

Be weary of this number
Sounded like it was in a call centre, noises in the background
Lady with an Indian sounding accent called saying my IP address has gone from private to public. Hung up when I was giving her BS answers

calls and doesn't answer

Caller: Insurance scam

Gives a missed call text without actually calling you - listed as a Potential Fraud number by Samsung and claims to be a Chinese insurance company on a callback. Do not fall for this scam